Gac1,
Hope this helps. Equation is good as long as a consistent set of units is used.
The wave speed in a thin-walled pipe can be calculated from,
a = sqrt[K/rho]/sqrt[1+c*(K/E)*(D/e)]
where,
sqrt = mathematical symbol for square root
a = sonic velocity
K = bulk modulus of the fluid; for liquid water, K is approximately constant and is 300,000 psi (6.0685E9 Pa)
rho = fluid density
c = constant depending on pipe support conditions. Range is 0.85 to 1.0 with a typical value of 0.91
E = Young’s modulus of elasticity for the pipe material
D = pipe diameter
e = pipe wall thickness
TREMOLO